Transcript Scientific Method PowerPoint

Scientific Problem Solving
2
Scientific Methods
• Step-by-step procedures of scientific problem
solving are called scientific methods.
• Solving any problem
scientifically involves
several steps.
• The steps used can
vary from situation
to situation and
aren’t always done
in the same order.
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Recognize the Problem
• The first step in using a scientific approach to
solving a problem is recognizing a problem.
• A scientific problem is a question that can be
answered using scientific methods.
• To solve a problem, scientists must do
research using various sources of
information.
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Observe
• In order to be able to answer the question,
a scientist needs to plan and carry out an
experiment.
• First, he or she must make and record
careful observations about the subject.
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Observe
• Observations can be bits of information you
gather with your senses.
• Most scientific
observations are made
with your eyes and ears.
• You also can observe with
your senses of touch, taste,
and smell.
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Infer
• Observations often lead to inferences.
• An inference is a conclusion about an
observation.
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Form a Hypothesis
• After a problem is identified, a scientist
might make a hypothesis.
• A hypothesis (hi PAH thuh sus) is a
statement that can be tested.
• Hypotheses are based on observations,
research, and prior knowledge of a problem.
• Sometimes more than one hypothesis can
be developed.
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Form a Hypothesis
• Hypotheses differ from two other scientific
statements—scientific theories and scientific
laws.
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Test Your Hypothesis
• An experimental investigation is a series
of carefully planned steps used to test a
hypothesis.
• In any experiment, it’s important to carefully
consider what resources you will use and
how to conserve them.
• It’s also important to keep everything the
same except for the item or variable you are
testing so that you’ll know which variable
caused the results.
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Test Your Hypothesis
• The one factor that you change in an
experiment is called
the independent
variable.
• For example, in an
experiment, similarsized fig plants
received the same
amount of sunlight.
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Test Your Hypothesis
• They were planted in similar containers
with the same type
and amount of soil.
• The hypothesis to
test is that fig
plants grow best
when watered only
once a week.
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Test Your Hypothesis
• The independent variable is the number of
times he waters each plant in a week.
• The growth of the plants is the dependent
variable.
• A dependant variable is the factor, or
outcome, that will be measured in an
experiment.
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Plan the Experiment
• In order to test only one variable at a time,
scientists often use constants.
• Constants are factors in an experiment that
stay the same.
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Plan the Experiment
• Some experimental investigations also have
a control. A control is a standard used for
comparison.
• If a scientist wished to study the chemical
makeup of a soil sample. A control soil—
one of known chemistry— could be
analyzed first.
• That way, data from the sample of interest
could be directly compared to data from the
control soil.
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Do the Experiment
• In the fig plant experiment, plant A would
only be watered once, at the beginning of
the experiment.
• A second fig plant, plant B, would get
watered everyday.
• The third fig plant, plant C, would get
watered once each week. The experiment
would last one month.
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Do the Experiment
• Tables can be used for recording observations.
• These will list each plant and the number of
times it was to be watered.
Plant
A
B
C
Date
Plant
Leaf
Watered Height Color
Number of
Leaves
Dropped
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Do the Experiment
• Observations, which would include the height
of each plant, the color of its leaves, and the
number of leaves it dropped, if any, should be
recorded.
Plant
A
B
C
Date
Plant
Leaf
Watered Height Color
Number of
Leaves
Dropped
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Analyze Your Data
• Data are collected during any scientific study.
• Some data are numeric values such as the
length of an object or the temperature of
a liquid.
• Other data you collect may include
observations that use adjectives and phrases
such as faster, smaller, not as well as, and
greener.
• An experimenter must record and study the
data collected before he or she can draw
conclusions about an experiment.
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Analyze Your Data
• By the end of the month in the fig experiment,
the leaves still left on the plant that was watered
only once were brown and shriveled. It had lost
most of its leaves.
• The plant that was
watered everyday had
a few leaves left on its
branches, but these
leaves didn’t look too
healthy.
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Analyze Your Data
• The plant that was watered once each week
had grown the tallest.
• Many healthy
green-andwhite leaves
extended from
its branches.
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Draw Conclusions and
Communicate
• A conclusion is a statement based on what
is observed.
• It can be concluded in the fig experiment that
not watering a plant enough causes the leaves
to dry out and die.
• Watering a plant too much also causes the
leaves to die.
• Watering the plant once a week seems to be the
best schedule, of those tested, for a fig plant.
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Draw Conclusions and
Communicate
• The hypothesis was supported.
• But in order to make sure his conclusions
were valid, he should repeat his experiment.
• An important step
in the scientific
process is to
communicate the
results of an
investigation.
Section Check
2
Question 1
List the steps in the scientific method.
Answer
The steps of the scientific method are: identify
the problem, form a hypothesis, test your
hypothesis, analyze your data, and draw
conclusions.
Section Check
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Question 2
What is an independent variable in an
experiment?
Answer
An independent variable is the factor that you
change in an experiment.
Section Check
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Question 3
Compare and contrast an observation and an
inference.
Section Check
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Answer
An observation is information gathered by the
senses. Observations can be something you
see, hear, smell, taste, or feel. An inference is a
conclusion about an observation. It is a guess
as to why something occurred.
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